You can pedal a bike just well enough to get by, or you can pedal
a bike efficiently and get the most out of the incredible mechanical
advantage that's available. To make the most of your gearing and
aerodynamics you must use all the leverage available at your bike/body
connection - your bike's crank arms. For anyone who's tried to loosen
a tight nut or bolt with a wrench, the advantage of maximum leverage
is simple to understand. This same leverage principle applies to
optimal energy transfer at your crank arms. To loosen that bolt,
or apply more pressure to the cranks, the force applied should be
perpendicular (at a 90 degree angle) to the lever/crank, and the
further from the pivot point that you push on the lever/crank the
more force you can apply. On a bike, the pivot point or fulcrum
is the axle of your bottom bracket, and the length of your lever/cranks
determines the maximum leverage. This potential won't change unless
you install longer cranks, but your cranks are likely already at
maximum length for effective pedaling in proportion to your leg
length. So this leaves the angle from which you apply pressure to
the crank arm as the only variable you can modify (besides increasing
force/wattage output from the engine—you). This is challenge
for some cyclists, but the rewards are well worth the effort!

The simple exercise of just pushing down on the cranks to make
the bike move becomes more complicated. As an example of wasted
energy: consider what happens when you simply push straight downward
with the crank arms at the 12:00 o'clock and 6:00 o'clock positions—absolutely
nothing. We all learned this early on when we struggled through
our first few pedal strokes on that little tricycle or coaster-brake
bike. Have you ever watched a child try to get his or her bike moving
when the pedals are in this position? After a while it becomes clear
that in order to get the child started you have to either give a
push, or pick the bike up and rotate the cranks 90 degrees to 3
and 9 o'clock positions. Optimal pedaling technique is no more natural
than a perfect swim stroke, it must be learned.

Figure 1. The difference in the leverage potential of the
right crank arm with pedaling force applied from two different directions
(clockwise crank rotation).

These examples are leading up to a thorough analysis of how to
push in powerful circles with your legs. Figure 1 examines the critical
range of motion over the top of the pedal stroke. This particular
point of the pedal stroke can be either a powerless 'dead spot,'
or an extra bonus bit of energy with a little technique work. The
challenge is to push your foot forward over the very top of the
stroke, and then continue the forward pressure as you begin your
down stroke. Figure 1 illustrates the optimal direction of force
(A) and the more typical, yet less effective direction of force
(B). Figure 1 also shows the amount of leverage available with the
average Pedal stroke (B), and the more efficient technique A). The
diagonal line (A) which runs parallel to the crank arm represents
the effective length of the lever when the pressure is applied perpendicular
to the crank. The two lower lines (A) and (B) compare the difference
of the effective lever length when the power is applied from direction
(A) or (B). Notice that pushing from angle (B) directs about one
third of the energy to pushing the crank arm toward the bottom bracket.
This is similar to pushing the crank straight downward when it's
at the 12 o'clock position. Direct downward force at the fulcrum
(bottom bracket axle) contributes nothing to the turning or torque
movement necessary to pull on the chain at the chain-rings, which
in turn pulls on the sprockets at the back wheel. Therefore, with
an equal amount of muscular power available, pushing only downward
(B) can generate only two-thirds the force that is possible by pushing
both forward and down simultaneously (A). In the weight room, the
leg extension machine, (not the leg press) which focuses on pushing
your lower leg forward from the knee, works well to develop this
particular muscle action by developing your vastus-medialus (inner
quad just above the knee).

But how can you develop your pedal stroke to improve this part
of your stroke without going to the weight room? The most obvious
is simply to get a feel for forward pressure at this part of the
pedal stroke while sitting on your bike in a static position. To
get a good feel for this while moving, try the pedaling with one
leg drill. To do this, just click one foot out of the pedal and
push forward, down, pull back and lift up on the "back stroke" with
only one leg. Apply some resistance like light braking or do the
drill on a slight uphill in a low gear, and try to feel an even
pressure all the way around in a smooth circular motion. If your
pedaling motion with one leg is jerky, or worse still, if there
are points where your freewheel is not engaged at all, keep working
on it. These "dead spots" where you apply no power are clearly the
weak spots in your pedal stroke; you can become more efficient and
therefore faster by getting a feel for where you could apply more
power.

Here is another obvious reason to refine your pedaling technique.
As you pedal, your leg must move from the bottom-most position,
back up to the upper-most position at the top of the pedal stroke
with each rotation of the cranks. Let's call this upward motion
the "backstroke" or "recovery." Now let's assume each of your legs
weighs 15 pounds. If you generate absolutely no lifting energy with
that recovery leg, then you're using up 15 pounds of your downward
force from your quadriceps of the opposite leg to push that recovery
leg back up. What a waste of energy! The hip flexor is the muscle
that can lift your leg up during this pedaling recovery or backstroke.
It is a relatively weak muscle, but well developed in runners, and
quite capable of lifting the full weight of your leg repeatedly,
thus nullifying the energy loss of pushing your leg back up at each
rotation.

So I've talked about the possibility of increasing efficiency and
power by pushing forward over the top of the pedal, stroke, and
lifting the weight of your leg on the recovery or backstroke, but
there's one more critical point of the circle where we can increase
energy output. This is the range of motion between points (4) and
(6) on Figure 2. At this point of the pedaling action we can use
our well developed runners' hamstring muscles. I know many of you
with cleated bike shoes already utilize this part of the pedal stroke
to your advantage. This pulling back motion can be the second most
powerful part of the stroke when you get it right, after the dominant
downward push from your quadriceps muscle group. The sensation of
pulling backwards from an extended leg should feel like scraping
something off the bottom of your shoe while standing in place on
the other leg.

Figure 2. Optimal foot angle relative to lower leg at various
points in the pedal stroke as viewed from the right side (clockwise
rotation).

Figure 2 illustrates an idealized pedal stroke with the best possible
angle of your feet relative to your lower leg to generate the most
power around the circle. You might say, "I just watched a bike race
on TV and the pro racers didn't pedal that way." If you watch closely
though, you will see that the slower their cadence, the more they
drop their heel (flatten the angle of their foot relative to the
ground) over the top of the pedal stroke. Typically when you are
spinning (pedaling fast with little resistance) you don't need to
generate much power and your foot favors the least possible movement
at the ankle, thus maintaining a perpendicular angle to your lower
leg all of the way around. But as you pedal more slowly, perhaps
needing more power for a climb or to fight a headwind, modifying
the angle of your foot at various points of the pedal stroke can
dramatically increase your power. Here's why: The power that your
dominant quadriceps muscle can generate increases as your leg straightens.
This can be easily demonstrated by experimenting with the amount
knee flexion versus max weight lifted on a leg press machine. So,
you already know a longer crank arm can give more leverage, but
on the other hand, the less you bend your knee the more powerful
your push. Obviously, this is a bit of a conflict on a bike, due
to the large circle created by each crank rotation When you understand
these two limitations, it follows that if you can pedal with a straighter
leg you should be able to apply more power at the crank arm. The
only way to do this is to bend your knee less, which can only be
accomplished by your knee rising less at the top of the pedal stroke.
Dropping your heel, keeping your foot flatter relative to the ground
over the top of the pedal stroke is the only way to do this. You
can see this change in pedal stroke in comparing spinning with low
pressure, then on the saddle while climbing hard at low cadence.
The difference between the heel high or heel low position over the
top is small but it can help you develop more power when you need
it. This even applies during the current trend toward spinning;
even Lance changes his stroke when more wattage is needed for short
periods.

Take a look at Figure 2 from point (2) to point (5). Over this
range of the circle the angle of foot to lower leg changes, from
flexed (flatter) to extended (pointed slightly downward). This is
the only area of the pedal stroke where the calf muscle gets to
contribute some force by contracting during the pedaling action.
But, take note though, that this extra energy contribution can't
happen if your foot is already pointing slightly downward at points
(2) and (3). So, from these last two paragraphs, we've learned of
two reasons that the angle of our foot to lower leg is critical
to pedaling efficiency. This flexion at the ankle requires moderate
flexibility of the joint but I've never seen a runner who doesn't
have the ability to do this on the bike. I should also say that
in some old school cycling manuals this technique is called "ankling,"
and requires much time a patience to develop. Of course you could
ride 20k a year like professional bike racers and the proper pedal
stroke will probably come without even thinking about it!

These various ranges of the pedal stroke individually contribute
vastly different amounts of power, because of inherent physiological
muscle strength limitations. I estimate that the forward push over
the top contributes about 10%, the down stroke about 65% (including
the small calf push near the bottom), and the pull back about 25%.
Even though the muscles are working to lift the weight of the leg,
the lifting action on the recovery probably contributes little or
nothing for most cyclists on a flat road. But when standing on the
pedals (while out of the saddle), sprinting/accelerating, or at
low rpm on a climb, the hip flexors and hamstrings should supply
a significant amount of temporary power. A significant amount of
force can be generated by pulling up for short periods, but only
when you really need it.

So far I've mentioned the term "spinning" with only a brief description
when in fact, to develop a smooth spin should be a prerequisite
to all the aforementioned power improving techniques. I've left
spinning for last because it's recommended that you do the bulk
of your spin work during the off-season base mileage building period.
Most bike racers, who've come through the USCF system had to race
with a gear restriction until a certain age. The reason for this
is to develop a proper pedaling action, and to save young tendons
and joints from the stress of over gearing. Spinning is useful because
the unusually fast rate of muscle contraction teaches your neurological
system to send each muscle stimulating electrical signal at exactly
the correct moment. In order for each of these intricate pushing,
pulling, and lifting operations to take place a very specific muscle(s)
must contract and then relax. It's not uncommon for the "uneducated
leg" to have opposing muscles contracting at the same time, and
this is very inefficient. Spinning is defined as a cadence of greater
than 95 rpm, and typically less than 120 rpm on the road. Most bike
racers can spin smoothly with no bounce on the saddle to significantly
over 120 rpm. The best way to develop your spin is to self-impose
a gear restriction for a certain stretch of road. Be patient, because
spinning takes time to master. Easy, or 'active recovery' are
ideal days to practice spinning in-season.

To get the most out of your cycling, you need to analyze your pedal
stroke and identify the weak spots. There's more involved with efficient
pedaling than just pushing downward with a lot of force. I've identified
three points of your pedal stroke where you can gain energy output:
Pushing forward over the top, pulling back at the bottom, and lifting
the weight of your leg as it moves back up to the top during the
'backstroke.' Cycling isn't a natural motion that we've repeated
every day since childhood, like walking is for running. Try to develop
this pedaling power flow as I've described; it will be worth the
effort. Without any extra work to increase aerobic capacity you
can gain speed by perfecting your pedaling technique.